Stock cleaner and method

ABSTRACT

Centrifugal separation of heavy and light impurities from waste paper stock in a centrifuge chamber is effected by removing the heavy impurities at the outer perimeter of rotation of the mass and extracting light impurities through an outlet drawing from the center of the mass in the opposite direction from recovery of stock from the mass. In a typical separator unit a cylindrical chamber receives the raw material tangentially adjacent to one end of the chamber and has a heavy impurity collection region leading off tangentially adjacent to the opposite end of the chamber, with cleaned stock outlet means at said opposite end, and a light impurities extracting outlet in the form of an axially adjustable duct leading from said one end of the chamber, such duct being open to atmosphere. Air pressure assistance for light stock extraction may be provided.

United States Patent 1191 Baggaley Jan.7,1975

1 STOCK CLEANER AND METHOD [75] Inventor: Jack Baggaley, Bury, England [73] Assignee: Beloit Corporation, Beloit, Wis.

[22] Filed: Jan. 12, 1973 [211 Appl. No.: 323,250

[30] Foreign Application Priority Data Jan. 28. 1972 Great Britain 4082/72 [52] U.S. Cl 2.09/17, 209/211, 209/250, 241/4617 [51] Int. Cl B03b 7/00 [58] Field of Search 209/144, 211, 17, 250; 210/512 R; 162/55, 261; 241/46 R, 92, 79.3, 46.17, 46.11

[56] References Cited UNITED STATES PATENTS 2.717.695 9/1955 Martin 209/211 2.743.815 5/1956 Goodwin 2.925.177 2/1960 Troland 209/211 3.172,844 3/1965 Kurz 209/211 3.310142 3/1967 Perkins et al.... 209/17 X 3.405.803 10/1968 Bahr et al. 209/211 3.421.622 1/1969 Wurtmann .1 209/211 3,425,545 2/1969 Zemanek et a1. 209/211 X 3.454,163 7/1969 Read 209/211 X 3,565,350 2/1971 Combs et al 241/4617 X 3,690,571 9/1972 Luthi 209/250 X 3.774,853 11/1973 Seifert 241/4611 FOREIGN PATENTS OR APPLICATIONS 1.057.135 3/1954 France 210/512 R 68,199 4/1958 France 209/211 OTHER PUBLICATIONS Tangel et al., Wet Cyclones". Chem. Engng. 62. No. 6 (June 1955) p. 234.

Primary I:'.\'umincr''Iim R. Miles Assistant l;'.\'amincr-Ralph J. Hill Attorney, Agent, or ["irm-Hill, Gross. Simpson. Van Santen, Steadman. Chiara & Simpson [57] ABSTRACT Centrifugal separation of heavy and light impurities from waste paper stock in a centrifuge chamber is effected by removing the heavy impurities at the outer perimeter of rotation of the mass and extracting light impurities through an outlet drawing from the center of the mass in the opposite direction from recovery of stock from the mass. In a typical separator unit a cylindrical chamber receives the raw material tangentially adjacent to one end of the chamber and has a 10 Claims, 3 Drawing Figures PAIENTEDJAN 7197s @w Y K WNW STOCK CLEANER AND METHOD This invention relates to separator units and more particularly to a separator unit for removing impurities from stock, particularly waste stock, intended for use in paper or board making machines.

In the paper and board making arts there is an increasing interest in the use of stock made from waste, such as waste paper, particularly for use in forming the intermediate plies in multi-ply paper or board. A difficulty with stock made from waste materials is that of cleaning the stock of heavy and light impurities which must be removed before the stock can be used.

In one conventional apparatus for cleaning light and heavy impurities the waste material and water are fed to a chamber and rotated about a substantially horizontal axis by a rotor mounted adjacent one wall of the chamber. The waste is broken down or pulped by the rotational. movement of the stock and the rotor and stock is discharged from the stock chamber through openings, generally defined by an annular screen plate, in the wall adjacent the rotor.

The heavy impurities, that is to say impurities having a specific gravity greater than 1 are caused to flow outwardly from the axis of rotation by the rotating stock and said impurities are collected in a channel or recess in a chamber wall remote from the rotational axis of the stock.

The light impurities, that is to say impurities having a specific gravity less'than l, are caused to move inwardly towards the axis of rotation by the rotating stock and, at said axis, said impurities are plaited into a rope by the stock, and the rope is continuously extracted from the chamber through an opening, lying substantially concentric with the axis of rotation, in a wall opposite said rotor.

The rope of light impurities is started off by inserting a rope, with a wire bait on the end thereof, through the opening into the stock, collecting impurities on the wire bait, and then slowly withdrawing the rope as the plaited rope of impurities becomes self-supporting.

A serious difficulty with this known arrangement is. that only large impurities which can be plaited into the rope, or can adhere to the rope, are removed and small light impurity bodies not removed by the rope pass with the cleaned stock through the wall openings.

A principal object of the present invention is to provide a new and improved separator unit for cleaning stock.

According to the present invention a separator unit comprises a stock centrifuge chamber, a stock inlet duct for supplying stock into said chamber, cleaned stock outlet passageways in an end wall of the chamber and a waste outlet comprising a duct, projecting into the chamber on the axis of rotation of stock centrifuging in said chamber, for tapping off light weight impurities adjacent the rotational axis of the stock.

Preferably stock in the centrifuge chamber is at a pressure in excess of atmospheric pressure and in one embodiment of the invention the stock is caused to centrifuge by establishing a pressure difference between tangentially inflowing stock and the axially exhausting cleaned stock. Alternatively, or in addition to the high pressure difference between the tangentially inflowing stock and the outgoing cleaned stock, the stock within the chamber is caused to centrifuge by an impeller or pulper mounted for rotation adjacent the clean stock outlets and rotated by a drive motor located externally of the chamber.

According to one aspect of the present invention there is provided a waste outlet, at a maximum diameter region for stock in the centrifuge chamber, for extracting heavy impurities centrifuged outwardly by rotating stock in the chamber.

Preferably the waste outlet for light impurities comprises an open ended tubular duct lying with its axis on the axis of rotation for the centrifuging stock and arranged to be axially adjustable with' respect to said chamber.

In one preferred embodiment in accordance with the invention the light impurities outlet comprises a cylindrical duct, open at both ends, disposed in a sliding bearing in an end wall of the chamber. A collar, or sleeve, rigidly secured to the tubular duct presents two diametrically opposed arms which are connected to the pistons of two hydraulic piston and cylinder arrange ments disposed one on either side of the tubular duct and in parallel relationship therewith. Thus, with the above arrangement the inner end of the tubular duct can be axially adjusted relative to its supporting wall of the centrifuge chamber thereby to allow the inner open end to be adjusted to the axial position most suitable for the collection of light impurities.

Preferably the tubular duct has a smooth wall bore of substantially uniform cross section which affords unobstructed flow of impurities therealong.

In one preferred method for operating the separator unit, the inflowing stock and the outflowing stock pressures are adjusted to establish within the stock rotating in the chamber an air core having a diameter slightly less than the internal diameter of the waste outlet duct. The provision of such an air core allows the light impurities to be extracted from the chamber with a minimum loss of stock and many types of impurities can be caused to flow along the stock surface towards and through the outlet duct by releasing air into the air core at the end of said core remote from the outlet.

According to this aspect of the invention there is provided means for introducing air into an air core at a location remote from the waste outlet duct whereby the air in said core flows towards and through said outlet duct.

Preferably the air is introduced into the air core from a duct passing axially through the rotor.

Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawing although variations and modifications maybe effected without departing from the spirit and scope of the novel concepts embodied in the disclosure, and in which:

FIG. 1 is a horizontal vertical sectional view taken substantially along the line II of FIG. 2 through a separator unit in accordance with the invention;

FIG. 2 is a vertical sectional view through the separator taken substantially along the line II-II of FIG. 1; and

FIG. 3 is a diagrammatic vertical sectional view through the rotational axis of a separator unit similar to the embodiment shown in FIGS. 1 and 2 but having an arrangement for introducing air into an air core in the centrifuging stock.

In the example illustrated chamber 11 is defined by a casing comprising a tubular wall I2 closed at one end recessed region in the wall 12 adjacent to the end plate 14 for collecting heavy impurities centrifuged out of the stock in the chamber 11.

The end wall 13 has a central opening 13a therein and an outwardly extending cylindrical member 18, flanged internally at its inner end at 18a and externally at its outer end at 18b is secured in the opening 13a and defines a sliding bearing for a tubular duct 19 axially located with respect to the chamber 11. Three packing rings 20, 21, and 22 are located within the bore of the cylindrical member 18 and are axially compressed against the flange 18a by the inner end of a cylindrical member 23 which has on its outer end an external flange 230 connected to the external flange 18b by bolts 23b. The packing rings 20, 21 and 22 form an effective fluid-tight seal between the cylindrical member 18 and the duct 19. The duct 19 has a yoke 24 secured thereon and providing diametrically opposite arms 24a and 24b to which two piston and cylinder actuator or motor means, generally indicated by numerals 25 and 26, are connected to provide axial drive for the duct 19.

The end plate 14 has a central opening. 14a through which the boss 27a of an impeller 27 projects. The impeller has blades 27b protruding axially from the boss 27a and radial blades 27c which serve to impart rotary motion to stock within the chamber 11 and further assist pulping of stock in the chamber.

The boss 27a is mounted on a driving shaft 28 which passes outwardly of the chamber 1 1 through a chamber 29, defined by a casing end closure 30 attached to the casing of chamber 11, and through a bearing 31 in the closure 30 to a drive means, generally indicated by numeral 32. A stock outlet duct 33 leading from the preferably lower portion of the closure 30 is provided for draining stock from the chamber 29..

The separator unit described above operates as follows:

With drive means 32 operating to rotate the impeller 27 the blades 27b and 27c cause the stock in chamber 11 to rotate about the axis of the chamber 11 and the radial blades 27c further serve to assist pulping of the towards the cylindrical wall 12, and eventually to the tangential trap 17, whilst the light impurities are displaced towards the axis of rotation of the stock where they are removed by way of the outlet provided by the tubular duct 19. Stock flows continuously through the perforate annular region into chamber 29 for removal throughthe outlet duct 33. It should be observed at this point that the perforate annular region 15 has its outermost diameter spaced inwardly from the cylindrical wall 12 and its inner diameter spaced the same distance from the'opening 14a in the end plate 14.

Thus, as waste stock is continuously supplied to the chamber 11 through the duct 16 and continuously exhausted through the perforate annular region 15 the stock in the chamber 11 is continuously flowing along the chamber 11 towards the wall 14 and as the heavy and light impurities are being continuously urged outwardly and inwardly, respectively, only clean stock in the annulus between the heavy and light contaminated stock is tapped off through the annular region 15 of the end plate 14.

The heavy impurities are, as stated above, centrifuged towards the cylindrical wall 12 of the chamber ll and as heavy contaminated stock is continuously tapped off by way of the tangential trap 17 a continuous flow of heavy contaminated stock is established within the chamber 11.

The light impurities, as stated above, are centrifuged towards the axis of rotation of the stock and can be tapped off by reciprocating the tubular duct 19 along the axis of rotation of the stock, by supplying pressure fluid to alternate ends of the cylinders of the piston and cylinder actuators 25 and 26 in known manner. Alternatively the tubular duct 19 can have a relatively static position, said tubular duct 19 being adjusted by the piston and cylinder arrangements 25 and 26 to locate the open end of duct 19in the best axial position for extracting, continuously, light contaminated stock from the rotating body of stock. It will be appreciated that the best fixed position for the open end of duct 19 will depend upon the rate of stock flow, the speed of rotation, and quality of the stock for a given unit. Variation of one or more of these characteristics may require adjustment of the location of the end of the duct 19, which adjustment can be readily carried out using the piston and cylinder actuators 25 and 26.

It will be observed that the duct 19 is open at both ends and it has an unobstructed bore so that the core of the stock within the chamber 11 is exposed to atmosphere. The stock inlet and outlet pressures and the speed of rotation of the stock are all controlled to establish within the rotating stock an air core extending from the rotor 27 to the waste outlet in the duct 19 with the diameter of the air core adjacent the waste outlet slightly less than the diameter of the bore of the duct 19.

With-this arrangement considerable benefit is obtained because an annular stream of stock is continuously being tapped off from the core of the rotating body of stock, the evacuation of stock from the core causes current flows towards the waste outlet along the stock surface region at said core and thereby the greater part of the light impurities centrifuged to the core of the rotating stock is conveyed towards the waste outlet duct 19 by the current flows at the stock surface.

FIG. 3 shows a modification to a separator unit of the type shown in FIG. 1 which greatly assists in the removal of light impurities from the region of the air core. In this arrangement an air passageway 34 passes axially through the rotor 270, the shaft 28, a coupling 35, and a drive motor shaft 36. An air coupling 37 is attached to the end of motor shaft 36 remote from the rotor 27a, through air tight bearing means, whereby the passageway 34 communicates with a conduit 38 connected to a pressure air source 39.

With the above arrangement air is continuously released into the air core adjacent to the rotor and air flow towards the'waste outlet duct 19 is thereby established. As the light impurities centrifuged to the core of the rotating mass of stock have a density less than the density of the surrounding stock such impurities project from the surface of the stock at the air core and are thus exposed to the air flow whereby said impurities are blown by the air flow away from the impeller 27 and towards and out of the waste outlet 19.

Provision of the air core serves two purposes, in that the evacuation of light impurities at the liquid/air surface is facilitated, and recirculation and distribution of light impurities from the core region of the stock back into the stock body, due to the rotor action, is severely reduced.

Although the present invention has been described by way of example with reference to a specific embodiment of the separator unit according to the present invention, many modifications and variations of the invention will be apparent to persons skilled in the art without departing from the spirit and scope of the invention. Thus, by way of example, the chamber 11 may be instead of cylindrical, in the form of a frusto-conical shape and in such a construction the end wall 14 may define the large end of the casing 12 and the heavy contaminants trap may conveniently be located atthe largest diameter of the chamber 11.

I claim as my invention:

1. In a stock separator unit comprising a tubular wall providing a stock centrifuge chamber having opposite spaced end walls:

a stock inlet opening tangentially through said tubular wall into said chamber adjacent to one of said end walls;

a tangential heavy impurities trap in the tubular wall adjacent to the opposite end wall and extending in the same direction of rotation as said inlet;

said opposite end wall having therein an annular perforate area spaced a limited distance from said tubular wall;

a rotary impeller concentric with said annular area and operating to impart rotary motion to stock within the chamber and assisting pulping of the stock;

a duct extending through said one wall concentric with the axis of rotation of the stock in the chamber for tapping off light impurities centrifuged toward the axis of rotation;

means providing a takeoff chamber to receive an annular stream of stock tapped off from the body of stock in the stock chamber through said annular perforate area;

and a stock outlet duct leading from the lower portion of said takeoff chamber.

2. A unit according to claim 1, including actuating means for adjusting said axial duct for optimum location of its inner end within said chamber.

3. A unit according to claim 2, wherein said actuating means comprise a pair of double acting piston and cylinder actuators arranged one on either side of and attached to said axial duct exteriorly of said chamber and parallel to the axis of the axial duct for effecting the axial adjustments of the axial duct.

4. A unit according to claim 1, wherein said impeller has a boss extending through a complementary opening in said opposite wall concentric with said perforate annular area, blades protruding axially from the boss and functioning to cause an air core in the stock in said chamber and leading to said axial duct, and radial blades on the boss which serve to impart the rotary motion within the chamber and to further assist pulping of stock within the chamber.

5. A unit according to claim 4, including means for introducing air under pressure on the rotational axis of the impeller to improve the air core.

6. A method of separating stock in a separator unit comprising a tubular wall providing a stock centrifuge chamber having opposite spaced end walls:

introducing stock through an inlet opening tangentially through the tubular wall into said chamber adjacent to one of said end walls;

removing heavy impurities tangentially through a trap in the tubular wall adjacent to the opposite end wall and in the same direction of rotation as the stock introduced through said inlet; imparting rotary motion to the stock within the chamber and assisting pulping of the stock by rotary impeller concentric with an annular perforate area which is spaced a limited distance from the tubular wall;

centrifuging light impurities toward the axis of rotation of the stock in the chamber and tapping off the light impurities through a duct extending through said one wall concentric with the axis of rotation;

tapping off an annular stream of stock from the body of stock in the chamber through said annular perforate area into a takeoff chamber;

and removing stock from the lower portion of the takeoff chamber through a stock outlet duct.

7. A method according to claim 6, including actuating said axial duct to adjust its inner end for optimum location within said chamber.

8. A method according to claim 7, comprising operating a pair of double acting piston and cylinder actuators arranged one on either side of and attached to the axial duct exteriorly of the chamber and parallel to the axis of the axle duct and thereby effecting axial adjustments of the axial duct.

9. A method according to claim 6, including operating blades protruding axially from the impeller and thereby causing an air core in the stock leading to said axial duct, and operating radial blades on the impeller to impart rotary motion to the stock in the chamber and to further assist in pulping the stock within the chamber.

10. A method according to claim 9, including introducing air under pressure on the rotational axis of the impeller to improve the air core. 

1. In a stock separator unit comprising a tubular wall providing a stock centrifuge chamber having opposite spaced end walls: a stock inlet opening tangentially through said tubular wall into said chamber adjacent to one of said end walls; a tangential heavy impurities trap in the tubular wall adjacent to the opposite end wall and extending in the same direction of rotation as said inlet; said opposite end wall having therein an annular perforate area spaced a limited distance from said tubular wall; a rotary impeller concentric with said annular area and operating to impart rotary motion to stock within the chamber and assisting pulping of the stock; a duct extending through said one wall concentric with the axis of rotation of the stock in the chamber for tapping off light impurities centrifuged toward the axis of rotation; means providing a takeoff chamber to receive an annular stream of stock tapped off from the body of stock in the stock chamber through said annular perforate area; and a stock outlet duct leading from the lower portion of said takeoff chamber.
 2. A unit according to claim 1, including actuating means for adjusting said axial duct for optimum location of its inner end within said chamber.
 3. A unit according to claim 2, wherein said actuating means comprise a pair of double acting piston and cylinder actuators arranged one on either side of and attached to said axial duct exteriorly of said chamber and parallel to the axis of the axial duct for effecting the axial adjustments of the axial duct.
 4. A unit according to claim 1, wherein said impeller has a boss extending through a complementary opening in said opposite wall concentric with said perforate annular area, blades protruding axially from the boss and functioning to cause an air core in the stock in said chamber and leading to said axial duct, and radial blades on the boss which serve to impart the rotary motion within the chamber and to further assist pulping of stock within the chamber.
 5. A unit according to claim 4, including means for introducing air under pressure on the rotational axis of the impeller to improve the air core.
 6. A method of separating stock in a separator unit comprising a tubular wall providing a stock centrifuge chamber having opposite spaced end walls: introducing stock through an inlet opening tangentially through the tubular wall into said chamber adjacent to one of said end walls; removing heavy impurities tangentially through a trap in the tubular wall adjacent to the opposite end wall and in the same direction of rotation as the stock introduced through said inlet; imparting rotary motion to the stock within the chamber and assisting pulping of the stock by rotary impeller concentric with an annular perforate area which is spaced a limited distance from the tubular wall; centrifuging light impurities toward the axis of rotation of the stock in the chamber and tapping off the light impurities through a duct extending through said one wall concentric with the axis of rotation; tapping off an annular stream of stock from the body of stock in the chamber through said annular perforate area into a takeoff chamber; and removing stock from the lower portion of the takeoff chamber through a stock outlet duct.
 7. A method according to claim 6, including actuating said axial duct to adjust its inner end for optimum location within said chamber.
 8. A method according to claim 7, comprising operating a pair of double acting piston and cylinder actuators arranged one on either side of and attached to the axial duct exteriorly of the chamber and parallel to the axis of the axle duct and thereby effecting axial adjustments of the axial duct.
 9. A method according to claim 6, including operating blades protruding axially from the impeller and thereby causing an air core in the stock leading to said axial duct, and operating radial blades on the impeller to impart rotary motion to the stock in the chamber and to further assist in pulping the stock within the chamber.
 10. A method according to claim 9, including introducing air under pressure on the rotational axis of the impeller to improve the air core. 